Fluid-pressure operated mechanism



June 8, 1943. H. H. TURNER FLUID-PRESSURE OPERATED MECHANISM 5 She ets-Sheet 1 Filed 001;. 11. 1940 INVENIOR. HAROLD H. TURNER BY @4, D6. 2266/ ATTORNEY.

June 8, 1943. H. H. TURNER 2,321,264

FLUID -PRES SURE OPERATED MECHANISM Filed Oct. 11, 1940 3 Sheets-Sheet 2 INVENTOR. HAROLD H. TURNER ATTORNEY.

June 8, 1943. H. H. TURNER FLUID-PRESSURE OPERATED MECHANISM 3 Sheets-Sheet 3 Filed Oct. 11. 194

m H "mm mm MT n H M Patented June 8, 1943 FLUDJ-PRESSURE. OPERATED MECHANISM Harold H. Turner, Beloit, Wis., assignor to Fairbanks, Morse & 00., Chicago, 111., a, corporation of Illinois Application October 11, 1940, Serial No. 360,761

3 Claims.

This invention relates to fluid-pressure operated mechanism of the servo-motor type, having general utility as a force transmitting motor or relay, the present invention having particular reference to an improved oil-pressure operated servo-motor unit adapted particularly for use as an operating part of a governor responsive engine speed control assembly for internal combustion engines and the like.

The principal object of the invention resides in the provision of an improved, oil-pressure operated servo-motor unit of a greatly simplified and compact construction, which while capable of being readily employed in control systems of various types wherein devices of this character are required, is adapted in particular, for use in internal combustion engine fuel regulating systems. The improved servo-motor is especially adapted to provide a force transmitting relay for the engine speed governor, such that within practical limits, any number of fuel regulating devices may be readily and positively controlled in response to the dictates of a single governor, as in the instance of a multi-cylinder engine of a size requiring an unusually large number of" fuel regulating devices. Thus by this provision, a smaller and much less powerful governor than otherwise would be necessary to the successful control of a given number of fuel regulating devices, may be utilized with complete effective ness.

Another object of the invention is to provide an improved servo-motor device of the character indicated, comprising a cylinder and a fluid-pressure actuated piston reciprocally displaceable therein and providing the force transmitting element of the device, wherein the piston is adapted further, for operation as a control valve in cooperation with cylinder inlet and discharge ports, to control the admission and discharge of the piston actuating fluid pressure relative to the cylinder and piston, the piston for this purpose being rotatable in the cylinder and provided with inlet and discharge ports arranged for cooperation with the corresponding cylinder ports such that in any displacement position of the piston in the cylinder, the piston ports may be selectively registered with the corresponding cylinder ports upon piston rotation in one direction or the other, as may be directly effected by engine governor operation according to the exemplary disclosure herein, whereby to effect admission or discharge of fluid pressure relative to the piston and thus to cause piston displacement, the piston ports being further so formed and related to the cylinder ports as to be displa'ceable out of registry with the latter ports in response to piston displacement.

A further object lies in the provision of a servomotor of the character described, for use with an engine governor controlled, fuel regulating mechanism of an internal combustion engine, wherein the servo-motor is of a desirably compact and relatively light weight construction, and is of a balanced piston type, capable of maintaining any operative position of the piston within the operative range thereof.

A further object resides in the provision of a relatively light Weight but powerful servo-motor adapted to be utilized as an operating part of an engine fuel control mechanism, including an engine speed governor, wherein the servo-motor is arranged to function as the control force transmitting element of the governor, such that a smaller capacity and hence lighter weight governor than otherwise would be required, may be utilized with full control effectiveness, the smaller governor and light weight servo-motor contributing materially to a desirable reduction in the total weight of the fuel control assembly.

Other objects and advantages of the invention will appear readily from the following description of a preferred embodiment of the improved servo-motor, as exemplified in the accompanying drawing, in which:

Fig. 1 illustrates in sectional elevation, a preferred form of the servo-motor device, the view showing the device in association with an internal combustion engine shown in fragmentary part. only; Fig. 2 is a view in end elevation, of the servo-motor valve-control end showing the control arm in operative connection with an engine driven centrifugally actuated governor, the latter being shown diagrammatically for the purpose of the present disclosure; Fig. 3 is a sectional elevation as taken transversely of the servo-motor, along the line 3-3 of Fig. 1; Fig. 4 is a fragmentary sectional elevation similar to the View of Fig. l, but showing the servo-motor piston displaced from an initial position; Fig. 5 is a sectional elevation taken transversely of the servo-motor, along the line 5-5 of Fig. 4; Fig. 6 is a view in fragmentary perspectiveelevation, of the servo-motor piston,,illustratingthe control ports therein; Fig. 7 is a developed view of :the piston, as somewhat reduced in size, and Figs. 8, 9 and 10 each illustrates the piston in developed elevation, these views having the port's'superimposed thereon to illustrate the cylinder and pisthe cylinder cylinder chamber.

'nally flanged, as at 35, and

the creation of pressure .tainedby varying the the piston, .tion, the piston itself is adapted for operation, vin addition to its power ports 42 and 43 respectively,

ton poi't relations under given operative conditions of the servo-motor.

Referring to the drawing by appropriate characters of reference, the presently preferred embodiment of the improved servo-motor, comprises a cylinder l which in the present example is provided with an integrally formed, laterally projecting member or web ll terminating in a mounting flange l2, by which the servo-motor may be supported as on a portion 14 of the frame of an internal combustion engine (not shown) with which the motor is to be utilized. One end of the cylinder I0 is closed by an integral head I5 formed centrally thereof with an externally projecting boss iii, the head and boss being centrally bored in a direction axially of the cylinder, to receive therethrough a piston rod 18. The piston rod is journalled at the head end of the cylinder for both reciprocable and rotary movement,

by a suitable sleeve bearing l9 seated in the bore of the boss IS, a packing gland 22 being provided in the outer end of the bore 20'to prevent fluid seepage from within the cylinder past the rodbearing l9. 1

Arranged for reciprocable displacement within H! is a piston 23 comprising a piston head portion 24 and a relatively extended piston skirt 25 providing a chamber 21 interiorly of the piston and open at its lower end to the The piston head 24 is axially bored, as at 28, to' receive an intermediate portion of the piston rod, the rod being formed to provide on the portion 36, a circumferential flange 3! to which the piston head is secured,

or machine screws 32. The.

as by suitable bolts cylinder end 34 opposite the head end 15, is exteris closed by a removable closure or head member 36 which is secured to the flange by suitable cap screws 38. The head 35 may be sealed against fluid leakage at the flange connection, by a gasket 39.

'Reciprocable displacement of the piston in the the present example, by differentials between a coil type, compression spring 40 arranged between the piston head 24 and the cylinder head l5, and a fluid-pressure medium, such as oil, acting in the piston chamber 21 against the interior cylinder is effected in surface of the piston head '24 andthe piston rod Control of piston dipslacement is atfluid pressure effective on and according to the present invenflange 3 I or'force transmitting function, as a rotary or sleeve valve to control the admission and discharge of the fluid pressure medium relative to the piston chamber 27.

Diametrally aligned fluid inlet and discharge are provided in the cylinder section intermediate the cylinder ends, in a position such that with the piston in the extreme of its reciprocable or displacement travel toward the removable cylinder head 36, these ports are adjacent the piston head 24 on the piston skirt side, as indicated in Fig. 1. An external cylinder boss 44 at the zone of the cylinder inlet port 42, provides a connector nipple for afluid supply conduit 46 extending from a suitable engine driven pump 41 illustrated diagrammatically in Fig. 1. The pressure medium for operating the improved servo-motor may be the lubricating oil under pressure in the engine lubricating system, as herein diagrammatically illustrated in part, since such provides an excellent source of the fluid pressure necessary to opsuch oil as may be discharged from the servomotor through the discharge port 43, is returned to the engine lubricating system. As shown by Fig. 1, leading from the discharge port 43 is a discharge passage 5E formed by preference, in the cylinder mounting web I! and flange l2, the passage 50 in the assembly of the servo-motor to the engine, registering with an opening 5| in the engine frame portion I4. The frame opening 5! may be in the crankcase zone of the engine so as to communicate directly with the crankcase oil chamber 48, for the direct return to the engine lubricating system, of oil discharged from the servo-motor during its operation.

From the foregoing and aswill appear more fully hereinafter, admission of oil under pressure through the cylinder port 42 to the piston chamber 21, as through piston port means later to be described, will effect longitudinal displacement of the piston in the direction of the cylinder head 15 and against the opposing force of the spring 40. Such piston movement projects the force transmitting end 52 of the piston rod 48 outwardly of the cylinder head end, to cause ll and extending to and connecting with the cylinderdischarge passage 5!]. Discharge of oil from within the piston chamber 21, as through a piston discharge port (later to be described) in register with the cylinder port 43, will effect an opposite displacement of the piston in the cylinder, as aided by the spring 40, to retract the piston rod end 52 and hence, further operate the fuel regulating means.

As before indicated, the piston 23 is adapted to serve as a valve element, to control the admission and discharge of the actuating fluid relative to the piston chamber 21. To this end the piston is rotatable about its axis within a predetermined angular limit, by control means presently to be described, and is provided in the skirt portion 26 thereof, with angularly spaced inlet and discharge ports 60 and 6| respectively, arranged so as to be selectively registerable with the corresponding cylinder ports 42 and 43. The ports 60 and 6! are right triangular in shape, as shown by the piston developed view of Fig. I, and extend longitudinally of the piston skirt such that the port margin '52 of each is parallel to the piston axis. Moreover, the triangular ports ,margin s thereof, serving a purpose presently to appear. 7 i

- As may be seen from Figs. 1, 6 and the piston I developed view of Figs..7 through 10, the piston ports are spaced about the piston skirt by a predetermined angular extent such that with the piston in a given angular position within the limits of its rotational displacement, longitudinal displacement of the piston in one direction, will result in moving the hypotenuse margin of one piston port over the associated cylinder port to a point of minimum port closure, while moving the similar margin of the other piston port to ward its associated cylinder port in the direction to open the latter, to a point of minimum port closure. At this stage, the cylinder inlet and discharge ports are just closed as indicated in Fig. 5, so that the piston will immediately come to rest in a position of balance, since the oil in the piston chamber 21 and communicating portion of the cylinder chamber is effectively trapped therein, to maintain a pressure on the piston counterbalancing the reaction of the spring 40 and such opposing force as may be applied to the piston rod by the mechanism controlled thereby. Thereafter, rotation of the piston from the aforesaid given angular position, serves to displace the hypotenuse margin of one piston port in a direction to open its associated cylinder port to the piston chamber 21, while displacing the similar margin of the other piston port beyond the associated cylinder port in the direction of port closure. Whereupon, oil will be admitted to or discharged from the piston chamber, depending upon the direction of piston rotation to effect opening of the cylinder inlet or discharge port, so that further longitudinal displacement of the piston will result, and continue until both ports are again closed in the manner above described. The piston then assumes a new position of balance, which normally, is not disturbed until further valve operation of the piston.

Turning now to the mechanism for accom plishing valve operation of the piston, the piston rod portion 56 extending from the piston connecting flange 3| thereof, axially through the piston chamber 21 and terminating at 68 inwardly of the lower or open end 69 of the piston skirt, is centrally bored longitudinally thereof, as at Ill, to receive a stub shaft 12. The stub shaft 72 is rotatably journalled in an externally projecting central boss 73 formed on the removable cylinder head 36, suitable packing gland means 14 'being provided in the shaft journalling boss 13 to prevent fluid leakage outwardly along the shaft. The outer projecting end 16 of the stub shaft has secured thereto, an actuating arm or lever 'i'! which may serve also, in cooperation with a shaft flange 78 engaging the inner sur-- face of the cylinder head 36, to limit or substantially prevent axial displacement of the stub shaft 12. The rotative connection of the stub shaft with the piston rod section 66 may be effected as in the present example, by a pin 80 rigidly mounted in the inner end portion 8| of the stub shaft to extend transversely thereof, and having its opposite projecting ends 82 closely received in opposed, longitudinal slots 84 provided in the piston rod section 66. The slots 84 provide for unrestricted reciprocable movement of the piston and rod, while the pin and slot connection of the latter with the stub shaft 12, enables rotation of the piston in direct response to rotation of the stub shaft. It is to be noted here that the provision for a relatively close fit of the pin ends 82 in the slots 84, providing only a minimum clearance for relative sliding movement of the parts, effectively precludes relative rotation of, or angular lost-motion movement between the stub shaft and piston rod section 66. Thus a given angular movement of the stub shaft 12 will produce a corresponding angular or rotative movement of the rod and piston.

In the present example, wherein the servomotor is utilized in the fuel control system of an internal combustion engine, the engine speed-responsive governor herein illustrated diagrammatically at in Fig. 2, is operatively connected to the stub shaft actuating arm ll through a suitable connection 85. Spaced stop elements 88 and 89 are provided on the cylinder head 38 to limit the angular swing of the arm 1'! and hence, to determine the limits of angular or rotational displacement of the piston in its valve function. According to the present embodiment, the stop 88 determines the initial or minimum operative position of the servo-motor piston, while the stop 89 determines the maximum operative piston position. Hence, the arm ll must be connected to the stub shaft 12 in a predetermined position relative thereto and to the initial position of the piston in the cylinder It. A suitable method of arm assembly to the stub shaft may be explained here as follows: The arm or lever ll is freely engaged with the stub shaft end 16, directed as shown and held against the stop element 88. Air under a suitable pressure is then supplied to the cylinder inlet port 42, while mechanical pressure is applied to the operating end 52 of the piston rod [8, tending to force the piston downwardly in the cylinder it! toward its limit of displacement adjacent the cylinder head 36. Under these conditions, the piston and rod are rotated, as by a wrench or other suitable means operating on the piston rod end 52, to bring the piston inlet port 60 into registry with the cylinder inlet port 62, at which time air under pressure will enter the piston chamber 21. Then by increasing the pressure applied to the piston rod, while continuing piston rotation to maintain the piston port 6!] in registry with the cylinder port 42, the piston may be displaced to its lower limit of travel, adjacent the cylinder head 36, at which time the large area portion 90 of the piston port 60 will be in full registry with the cylinder port 42 (Fig.3 and the developed view of Fig. 7). The hub portion 92 of arm ,11 and the stub shaft end 76 now may be drilled transversely therethrough and a connecting pin 93 inserted in the resulting through-aperture. The lever Tl, shaft 12 and the piston 23 are now definitely positioned in the desired operative relation, so that in connecting the lever 11 to the governor 85, the parts will be positioned as indicated in Fig. 2, wherein the governor is in its initial or inoperative position and holds the lever 11 against the stop 88.

The operation of the servo-motor as used on an engine to effect regulation of the fuel feed mechanism in response to governor operation, may be here briefly described to facilitate a complete understanding of the improved servo-motor. When the engine is not operating, the speed responsive governor 85 then being in it initial or inoperative position, will hold the piston-valve control lever 11 against the stop 88. The lever 11 so positioned, thereby determines the angular position of the piston 23 such that the piston inlet port 60 is in full-open registry with the cylinder inlet port 42, the piston 23 then being in initial position relative to its longitudinal displacement travel, or with the lower end 69 of the piston skirt 26 closely adjacent the lower'cylin'der head 36. With the piston positioned as described (Figs. 1 and 3), the piston discharge port 6| has its upper or small-area end portion 94 angularly removed from registry with the cylinder discharge port 43, so that the latter is definitelyclosed by the adjacent wall of the piston skirt '26, as indicated by thepiston developed view of Fig. 7. Now as the engine is started under no-load conditions, as by mechanical, pneumatic or other well known engine starting means, the engine lubricating oil pressure will build up to normal operating pressure, so that the oil admitted to the piston chamber 21 through the inlet ports 42 and 60, will cause longitudinal displacement of the piston 23 from its initial position. The resulting displacei ment of the piston serves to actuate the engine fuel control means 53 through the piston rod operating end 52 and the pivoted arm 54, to admit fuel to the engine cylinders. As piston displacement continues in the direction to bring the hypotenuse edge 64 of the piston inlet port 60 over the cylinder inlet port 42, the governor 85 operating in response to increasing engine speed,

actuates the lever 11 away from the stop 88, to cause clockwise rotation of the piston 23, as viewed in Fig. 3, and thus to move the hypotenuse edge 64 of the piston port 60 in the direction of the cylinder port 42. As a consequence of the substantially simultaneously occurring displacement and rotary movements of the piston, which continue during engine starting and until the engine attains its normal no-load runnig speed, the hypotenuse control edge 64 of the piston port 60 is displaced in the port-closing direction, as to pass over the cylinder port 42. When the engine attains no-load running speed, the governor in response thereto, halts further clockwise rotation of the piston 23, the control arm or lever 11 then being in a position intermediate the stops 88 and 89. At this time the cylinder inlet port 42 is very nearly closed at the hypotenuse edge 64 of the piston port 60, the lubricating oil pressure acting on the piston, continuing upward displacement of the latter to the slight degree necessary to bring the hypo tenuse edge 64 of the piston inlet port 60 over the cylinder-inlet port 42 in the direction of port closure, until it just effects closure of the latter port (Figs. 4, 5 and 8). In such position of the piston (Fig. 5), the hypotenuse edge 65 of the" closed. The piston then comes to a stop, since the inlet and outlet ports are now closed, Fig. 5 and also, as will be observed in the developed view of Fig. 8, to entrap the oil in the piston chamber 21, and communicating portion of the cylinder chamber, the piston thus attaining a position of balance and hence maintaining the engine fuel feeding means regulated to supply fuel sufiicient to maintain operation of the engine at normal, no-load speed.

As load is applied to the engine, the immediate effect is a reduction in engine speed which is reflected in the speed-reduced operation of the governor. The governor in response to "the reduced engine speed, moves the control'lever 11 toward the stop 88, which results in counterclockwise rotation of the piston 23 .(Fig. 5) to move the hypotenuse edge 64 of the piston inlet port 80 in the direction to uncover the. cylinder inlet port 42, as observed from the developed 1 view of Fig. 9, thus to admit oil to the piston chamber and cylinder." The resulting increase of pressure on the piston, serves to further displace'the'same' upwardly toward the cylinder head [5, against the counterforce of spring 40, tov further actuate the engine fuel feeding means in a manner to increase the fuel supplied to the engine. The engine speed thenincreases to'the normal running value under the load applied to the engine, and as the speed rises the governor actuates the control lever 11 in the direction away from the stop 88. The piston is thereby rotated in the clockwise direction, so that as a result' of the combined displacement and rotary movements of the piston 23, the hypotenuse edge 64 of the piston port 60 is rapidly displaced over and just effects closure of the cylinder inlet port 42. The cylinder discharge port 43 then being similarly just closed, as before described and as indicated by the developed view of Fig. 10, the piston comes to rest in a position of balance, so that the fuel control means is established in a condition to feed fuel in a quantity sufficient to maintain the normal speed operation of the engine under the applied load. As the engine load may be increased up to full load or to the predetermined permissible overload under which the engine may continue to operate for short periods, the same sequence of governor-servomotor operation as described in connection with the initial loading of the engine and as indicated broadly by the developed views of Figs. 8, 9 and 10, occurs to effect the necessary increase in the engine fuel supply, so that the engine may continue operation at normal rated speed under the given load. It is to be noted here that as a result of the combined displacement and rotary movements of the piston to effect relatively rapid control positionment of the hypotenuse edge 64 of the piston port 60 relative to the cylinder port 42, as above described, overrunning or hunting of the engine speed is substantially prevented,

since the governor responsive servo-motor b its quick action in attaining fuel regulation corresponding to the engine load and speed, has a sta- .bilizing function as well, in preventing over and under oscillations of engine speed.

Upon decreasing the engine loading, the speed of the engine tends to rise above the normal running speed, and this is reflected in the governor which then operates to actuate the lever 11 further'toward the stop 89. The resulting rotation of the piston 23 in the clockwise direction from the position thereof indicated in Fig. 5, serves to displace the hypotenuse edge 65 of the piston discharge port 6|, over the cylinder discharge port 43 to open the latter for discharge of oil from the piston chamber 2'5. During such piston rotation, the hypotenuse edge 64 of the piston inlet port 60, is moved beyond the cylinder inlet port 42 in the direction to continue closure of this port. As oil is discharged from the piston chamber 21, the pressure thereof on the piston is reduced, so that the spring 40 may then act to longitudinally displace 'the piston 23 downwardly in the cylinder ID, to-

ward the cylinder head 36. Such piston movement then actuates the fuel feeding means to decrease the quantity of fuel supplied to the engine, which thereby causes a reduction in engine speed to substantially the normal running value.

As the engine speed returns to normal running fuel reducing, downward displacement of the piston and the counterclockwise governor rotation thereof, occur substantially simultaneously, once the speed rise is checked and starts to decrease, so that the combined effect of the piston movements is to bring the hypotenuse edge 65 of the piston port 61 relatively quickly over the cylinder discharge port 43 in the direction to close the same, until the port is just closed, when further displacement movement of the piston ceases. The engine is then operating at normal running speed under the reduced load. Further reduction in the load to a no-load condition produces the same sequence of governor-servo-motor operation to regulate the engine fuel feed in a manner to maintain normal running speed of the engine. As before indicated in connection with the function of the control mechanism upon increasing engine loading, the servo-motor functions as well, during decreasing of the load, to prevent speed oscillations or hunting.

It will be observed now, that the servo-motor may function additionally, as a safety device to cause stoppage of the engine upon failure of the engine lubricating system to maintain the predetermined required oil pressure flow therein. For example, when for any reason the lubricating system fails to function or the oil pressure therein drops in any appreciable degree, the resulting inadequate lubrication of the engine bearings and other operating parts, will be reflected in a reduction in engine speed. The governor then actuates the lever Ii toward stop 88 to produce a counterclockwise rotation of the piston 23, which moves the hypotenuse edge 6 8 of the piston inlet port 60 over the cylinder inlet port 42 in the direction to open the port for admission of oil to the piston chamber 21. However, because the oil pressure has dropped or failed altogether, the oil pressure acting on the piston will be relieved, so that the spring 40 may then displace the piston downwardly toward the cylinder head 36, while at the same time, forcing the oil in the piston chamber out through the now open inlet ports 60 and 42. The downward displacement and governor-actuated counterclockwise rotation of the piston continue until the piston attains its initial inoperative position as first described. The servomotor thereby shuts-off further supply of fuel to the engine, so that the engine ceases operation. The cause of the lubricating system failure then may be ascertained and repairs made before the engine is again placed in operation.

As will be seen now, the present improved hydraulic or fluid-actuated servo-motor provides a compact and efficient device of this character, wherein the power transmitting piston thereof is adapted to function additionally, as the control valve for controlling the admission and discharge of the fluid actuating medium relative to the piston. While for the purpose of example only, the preferred embodiment of the device as herein illustrated and described, has been described as to its function, in connection with a governor responsive fuel regulating system of an internal combustion engine, it will be readily appreciated and understood that the servo-motor embodying the features of the present invention, may be employed to advantage in many forms of control systems requiring force-transmitting means of a relay or force-amplifying character, to which class the present servo-motor belongs.

Although the embodiment of the invention herein disclosed, is presently preferred, nevertheless the parts and assembly arrangement thereof may be altered or modified without departing from the scope and full intendment of the invention, as defined by the appended claims.

I claim:

1. A fluid pressure operated device of the character described, comprising a cylinder having single inlet and discharge ports for fluid under pressure, located in diametrically opposed relation intermediate the cylinder ends, a force-transmitting piston in said cylinder and displaceable in one direction by fluid pressure, resilient means acting on said piston in opposition to the fluid pressure on the piston, said piston being rotatable in the cylinder and formed to provide a hollow piston skirt having single inlet and discharge ports in opposite wall portions and extending longitudinally of the skirt, said piston skirt ports being of generally triangular form and relatively inverted to provide cylinder port controlling edges oppositely inclined relative to the longitudinal axis of the piston skirt, said skirt ports cooperating with the cylinder ports such that only one thereof may be registered with the corresponding cylinder port upon rotation of the piston and skirt in one direction, and further, such that upon displacement of the piston and skirt, both skirt ports will be positioned out of communicai tion with the cylinder ports, whereby the admission and discharge of fluid under pressure relative to the cylinder and hollow piston skirt, may be controlled so as to determine the displacement position of the piston in the cylinder, a shaft extending axially of the cylinder and through one end thereof, said shaft being secured to said piston and constituting the force-transmitting agency of the piston to the exterior of the cylinder, the inner end portion of said shaft being axially recessed, a rotatable element extending into said cylinder and received in said shaft recess, and a connection between said shaft and rotatable element for effecting piston rotation in response to rotation of said element.

2. In a control apparatus for an operating mechanism to be regulated, including a device for regulating the mechanism and means responsive to an operating characteristic of the mechanism for determining operation of said regulating device, a force-transmitting relay operatively connecting said characteristic responsive means to said device, said relay comprising a cylinder having single inlet and discharge ports for fluid under pressure, located in diametrically opposed relation intermediate the cylinder ends, a piston arranged in said cylinder fo both angular movement and longitudinal displacement therein, the piston being displaceable in one direction by fluid pressure in the cylinder, a spring tending to displace the piston against the fluid pressure, a shaft element extending axially of the cylinder and operatively connecting said piston to said regulating device, said piston including a hollow skirt having single inlet and discharge ports in substantially opposite wall portions thereof and each extending longitudinally of the skirt, the skirt ports being of generally triangular form and relatively inverted to provide cylinder port controlling edges oppositely inclined relative to the longitudinal axis of the skirt, said piston skirt ports cooperating with the corresponding cylinder ports for controlling admission and discharge of fluid under pressure relative to the hollow skirt and cylinder such that only one of the skirt ports may be registered with the corresponding cylinder port upon angular movement of the piston and skirt in one direction, and further such that upon longitudinal displacement of the piston and skirt, both skirt ports will be positioned out of registry with the corresponding cylinder ports, with the latter ports effectively closed by overlying Portions of the piston skirt, and means controlled by said characteristic responsive means and operatively engaging said shaft element, for efiecting angular movement of said piston and skirt.

3. A pressure actuated device for transmitting motion of a controlling mechanism to a mechanism to be.controlled thereby, comprising a cylinderand a piston rotatable therein and displaceable in onedirection by fluid under pressure, a spring tending to displace the piston against the fluid pressure, said cylinder having a single inlet port and a single outlet port, a hollow cylindrical valve member integral with the piston and provided with inlet and outlet ports fo cooperation with the corresponding cylinder ports, said valve ports being of generally triangular form and relatively inverted to provide cylinder port controlling edges oppositely inclined relative to the longitudinal axis of the piston valve member, so that in a given position of rotation and displacement of the piston and valve in the cylinder, said valve ports will be out of communication with the cylinder ports, whereby to efiect a condition of balance of the piston and valve in said given position, and

further such that upon rotation of the piston and valve in one direction or the other, one or the other of the valve ports will be thereby placed in communication with its corresponding cylinder port, for the admission or discharge of fluid pressure relative to the hollow valve and cylinder, whereby to cause displacement of said piston and valve until the valve ports are again out of communication with the cylinder ports, whereupon the piston and valve become stabilized in the changed rotary and displacement position thereof, a piston rod connected to said piston and adapted for operative connection to said mechanism to be controlled, for transmitting the displacement movements of the piston thereto, a control member provided by an extension of said piston rod, arranged within said hollow valve member and being slotted longitudinally substantially throughout its length, and. means including a pin seating in the slot of said control member, adapted for actuation by said controlling mechanism for causing through said control member, rotation of the piston and valve member.

HAROLD H. TURNER. 

